Description:The Hyattsville Armory is distinctly fortresslike, and on its knoll it occupies a strong defensive position. Offering a commanding view of the surrounding area, and patterned after a medieval English castle, the Armory, built of native stone, communicates strength and mystery. Rectangular turrets flank the arched limestone entranceway. The parapeted walls of the building are of 18" thick granite from nearby quarries laid up in random patterns with beaded mortar joints. While the parapets in the main section of the building rise only 30" above the roof, the turrets, measuring 7'-7" square, rise 15' above the roof surface. The reverse side of the "Great Seal of Maryland" is in limestone and appears above the main entranceway incorporated in the parapet. Originally, the fenestration of the front section of the Armory consisted of 9/9 and 6/6 sash windows on the first and second floors and 6/6 lights in the English basement. The first and second story windows were changed to 1/1 sash windows. In the assembly area to the rear of the building, six 15-light windows are arranged three over three, all of which open on a pivot. Beyond the assembly area is a three-story structure containing a garage flanked by offices and stairs which gain entry to the assembly area. Above the garage is the stage of the assembly area. The roof of the assembly area is supported by trussed steel bents which divide the walls into six sections. These sections are reflected on the exterior by stone buttresses in the walls which take the added thrust of these large roof supporting structures. Entrance to the foyer from the main entrance to the building is gained through a pair of segmented-head wooden doors each containing 20 lights in the upper section of each door, measuring 3'-9" wide by 9'-3" high. Another pair of these doors gain entrance to the assembly area after one passes through the foyer. The most notable feature on the interior is the ceramic tiled walls of the assembly area. Baseboards and chairrails are massive, simple, and uniformly intact throughout the building.

Significance:
The Hyattsville Armory is significant for both its architecture and its association with military history. It was the first Armory built in Prince George's County and the fifth in Maryland, and mightily continues the fortress-like nature of the four slightly earlier structures, namely Elkton in 1915, Bel Air in 1916, and Westminster and Cambridge in 1917. Its architect, Robert Lawrence Harris, served as State Architect under Governor Albert C. Ritchie. In this capacity, Harris would supervise the design of similar armories in Salisbury, Kensington, Silver Spring, Hagerstown, Laurel, Easton, Crisfield, Pocomoke City, Centreville, and Cumberland, as well as an addition to the armory in Frederick. Thus, the Hyattsville Armory is something of a seminal work. Further, the unit headquarters here has a service history that is distinguished in its own right: it has seen action from Mexico to Central Europe, has several international decorations, and has played a key role in establishing the American Legion.